Environment headlines - 28 Sept, 2005

EnvironmentSo who is right in debate on role of global warming?Andrew C. Revkin, NY Times ...What is clear is that an array of leading experts on oceans and climate agree that the tropical oceans have warmed in a way that is hard to attribute to anything other than overall warming of the climate from the buildup of carbon dioxide and other greenhouse-gas emissions.

It is also clear to many climate scientists and oceanographers that warmer oceans will eventually increase the intensity and rainfall of hurricanes, but not necessarily their frequency.

In fact, two recent studies of hurricanes, by different scientists using different methods, claimed to detect a big rise in hurricane intensity around the world over the last several decades.

But the authors of both analyses acknowledged that more data would be needed to confirm a link to human-caused warming. The murkiness arises because the relationship between long-term warming of the climate and seas is only perceptible in statistical studies of dozens of storms, not in the origin or fate of any particular storm. (24 September 2005)Author Revkin recently spoke about uncertainty and global warming at an AAAS talk.

Gulf currents that turn storms into monstersAndrew C. Revkin A month ago, Kerry Emanuel, an atmospheric scientist who has spent decades studying how hurricanes reach their peak strength, "had this terrible feeling of dread" when he saw that Hurricane Katrina's track in the Gulf of Mexico would carry it right over an oceanographic phenomenon known as the loop current.

Late Friday, Dr. Emanuel, from the Massachusetts Institute of Technology, felt the same dread when it seemed as if Hurricane Rita, fueled by the same current, was going to pass over a related warm eddy and grow even stronger.

To his relief, Rita did not, and that is one reason the storm weakened substantially before coming ashore.

In this stormy season, Dr. Emanuel and other storm experts have been fixated on the loop current, a great ribbon of hot water meandering through the Gulf of Mexico.

For a long time it has been little more than an oceanographic curiosity but, because of its role in energizing storms, it is now a centerpiece of hurricane forecasts.

The current is a conveyor belt of banked solar energy, typically with more than 100 times the flow of the Amazon. It gained notoriety after providing the fuel that helped transform Hurricanes Rita and Katrina from nondescript tropical storms into a rare single-season pair of Category 5 monsters. (27 September 2005)

The document, prepared by the U.N. Intergovernmental Panel on Climate Change and released Monday, recommends using existing and emerging technologies for capturing the carbon dioxide produced by power plants and factories before it enters the atmosphere.

Carbon dioxide is one of the gases believed to cause the so-called greenhouse effect, which is warming the earth's atmosphere and is widely believed to be the cause of the planet's increasingly bizarre weather patterns.

"While the most important solutions to climate change will remain energy efficiency and cleaner energy sources, this new report demonstrates that capturing and storing carbon dioxide can supplement these other efforts," said Klaus Topfer, executive director of United Nations Environment Program.

The report suggests emissions should be captured from sources such as electricity generation, refineries and oil plants, compressed and stored in geological formations, the oceans or in minerals, instead of being released in the atmosphere. (27 September 2005)

Sequestration RevisitedJamais Cascio, WorldChanging |"Carbon Sequestration" is sometimes suggested as a parallel process alongside a significant shift away from carbon-producing technologies. The logic is straightforward: carbon dioxide is still produced, but rather than remaining concentrated in the atmosphere for a century, it is extracted. This extraction can take place at the point of production (so-called "carbon capture") or more generally, using CO2-loving plants.

Although some may hope to use carbon sequestration as an excuse to delay or ignore a move towards non-carbon-emitting technologies, the reality is that the planet is close enough now to a potential climate tipping point that we should not rule out any effort that might help us forestall disaster. Moreover, as much as we would like to see all manner of CO2-producing industries (such as power production or cement manufacturing) move to cleaner technologies, even in the best likely scenario it's going to take decades for the transition to be complete. In principle, if CO2 output can be reduced from those industries during the transition, we're all better off.

But the IPCC (Intergovernmental Panel on Climate Change) wondered just what kind of effort would be required to make a real difference in CO2 output. The IPCC commissioned a study, and the preliminary results are now in. Read on for a discussion of our sequestration options. (27 September 2005)

In California, agriculture takes center stage in pollution debateJuliet Eilperin, Washington Post ...Agriculture does not occupy a prominent place in America's environmental policy debates, but farming has arguably more of an impact on the land, air and water than any other sector in the U.S. economy, environmental and industry experts say. In addition to producing airborne emissions, farms take up nearly half of the nation's land, and nutrient-laden runoff from farms affects such waterways as local streams and the Gulf of Mexico.

"The sheer scope of farmland means that unless it is extremely well-managed, it's going to create serious problems," said Tim Searchinger, an agricultural policy specialist at the advocacy group Environmental Defense. "But with some tweaks and a few bold approaches, farmers and ranchers could do a lot of good."

Michael Kleeman, an environmental and civil engineering professor at the University of California at Davis, estimates that agriculture accounts for as much as half of the valley's air pollution. (26 September 2005)

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